Computer simulation of the effect of changing abdominal thickness on the electrogastrogram.

The effect of different abdominal thickness on cutaneous recordings of gastric electrical activity (GEA) known as electrogastrograms (EGG) have not been adequately studied. The stomach was represented as a truncated conoid in spherical system of coordinates. Gastric electrical field was modelled using previously described methodology. Electrical voltages were calculated in simulated standard cutaneous recordings. The effect of increased thickness of the abdominal layers was quantitatively examined. Changes of the thickness of the abdominal layers significantly affected signal-to-noise ratio of EGG. When the critical abdominal thickness of 7 cm was exceeded, EGGs were quantified as abnormal although the internal GEA was normal. Computer modelling indicated that changeable abdominal thickness caused by the abdominal layers separating the stomach from the recording electrodes significantly influence the EGG recordings even if the layers are homogeneous.